Status Report

NASA Hubble Space Telescope Daily Report # 3491

By SpaceRef Editor
November 19, 2003
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HUBBLE SPACE TELESCOPE

DAILY REPORT # 3491

PERIOD COVERED: DOYs 318-320

OBSERVATIONS SCHEDULED

ACS 9984

Cosmic Shear With ACS Pure Parallels

Small distortions in the shapes of background galaxies by foreground
mass provide a powerful method of directly measuring the amount and
distribution of dark matter. Several groups have recently detected
this weak lensing by large-scale structure, also called cosmic shear.
The high resolution and sensitivity of HST/ACS provide a unique
opportunity to measure cosmic shear accurately on small scales. Using
260 parallel orbits in Sloan textiti {F775W} we will measure for the
first time: beginlistosetlength sep0cm setlengthemsep0cm setlength
opsep0cm em the cosmic shear variance on scales <0.7 arcmin, em the
skewness of the shear distribution, and em the magnification effect.
endlist Our measurements will determine the amplitude of the mass
power spectrum sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20,
and the mass density Omega_m with s/n=4. They will be done at small
angular scales where non-linear effects dominate the power spectrum,
providing a test of the gravitational instability paradigm for
structure formation. Measurements on these scales are not possible
from the ground, because of the systematic effects induced by PSF
smearing from seeing. Having many independent lines of sight reduces
the uncertainty due to cosmic variance, making parallel observations
ideal.

STIS 9973

Intensive Coverage of the Eta Carinae Event in 2003

For a variety of reasons, HST can provide a very special and unique
data set when Eta Car experiences its next spectroscopic event in
mid-2003. Explaining the phenomenon is only part of the motivation.
This star and its ejecta have unique characteristics that make them
important for several branches of astrophysics; and when a
spectroscopic event occurs, it’s like varying the parameters in an
experiment {or rather, set of experiments}. The 2003 event may be the
only chance in the forseeable future to obtain such a data set,
especially with HST. Eta Carinae has extreme parameters; it is
mysterious in surprisingly basic ways; and HST/STIS can gather useful
data on it at a terrific rate. As we explain below, the proposed data
set will be valuable in several independent ways: It will help solve a
specific set of current problems, it will constitute a large and
unique archival data base for both stellar and nebular astrophysics,
and it will be well-suited for educational uses.

FGS 9883

Parallaxes of Extreme Halo Subgiants: Calibrating Globular Cluster
Distances and the Ages of the Oldest Stars

The ages of the oldest stars are a key constraint on the evolution of
our Galaxy, the history of star formation, and cosmological models.
These ages are usually determined from globular clusters. However, it
is alternatively possible to determine ages of extreme Population II
subgiants in the solar neighborhood based on trigonometric parallaxes,
without any recourse to clusters. This approach completely avoids the
vexing issues of cluster distances, reddenings, and chemical
compositions. There are 3 known nearby, extremely metal-deficient Pop
II subgiants with Hipparcos parallax errors of 6-11% which are
available for such age determinations. At present, based on the latest
isochrones, the derived ages of these stars {HD 84937, HD 132475, and
HD 140283} are all close to 14 Gyr, uncomfortably close to or higher
than current estimates of the age of the universe. However, the errors
in the Hipparcos parallaxes imply uncertainties of at least 2 Gyr in
the ages of the 3 stars. We propose to measure parallaxes of these
three Pop II subgiants using HST’s Fine Guidance Sensor 1R. We expect
to reduce the Hipparcos parallax error bars by factors of 5-6,
providing the most stringent test yet of current theoretical stellar
models of Pop II stars and pushing the age uncertainties to below 0.5
Gyr. These data will also provide a major new constraint on the
distance scale of globular clusters, with wide implications for
stellar evolution and the calibration of Pop II standard candles.

NIC/NIC3 9865

The NICMOS Parallel Observing Program

We propose to continue managing the NICMOS pure parallel program.
Based on our experience, we are well prepared to make optimal use of
the parallel opportunities. The improved sensitivity and efficiency of
our observations will substantially increase the number of
line-emitting galaxies detected. As our previous work has
demonstrated, the most frequently detected line is Halpha at
0.7<z<1.9, which provides an excellent measure of current star
formation rate. We will also detect star-forming and active galaxies
in other redshift ranges using other emission lines. The grism
observations will produce by far the best available Halpha luminosity
functions over the crucial–but poorly observed–redshift range where
galaxies appear to have assembled most of their stellar mass. This key
process of galaxy evolution needs to be studied with IR data; we found
that observations at shorter wavelengths appear to have missed a large
fraction of the star-formation in galaxies, due to dust reddening. We
will also obtain deep F110W and F160W images, to examine the space
densities and morphologies of faint red galaxies. In addition to
carrying out the public parallels, we will make the fully reduced and
calibrated images and spectra available on-line, with some
ground-based data for the deepest parallel fields included.

ACS/WFC 9860

ESSENCE: Measuring the Dark Energy Equation of State

The accelerating universe appears to be dominated by a dark energy
with a significant negative pressure. The ratio of the pressure to
density of this mysterious energy {its equation of state} is an
observable which can differentiate between the proliferating candidate
theories. We propose to estimate the dark energy equation of state by
observing Type Ia supernovae at redshifts near z=0.7 with HST in
concert with the on-going ESSENCE NOAO Survey program that is
discovering and studying supernovae between 0.3<z<0.8. We show that an
interesting constraint on the equation of state can be made with
supernovae observed at modest redshifts given the current knowledge of
the matter density. We will follow 10 Type Ia supernovae discovered
from the ground and passed to HST without disrupting its schedule. The
full data set will constrain the equation of state to 10% and strictly
limit the range of possible dark energy models. In keeping with the
ESSENCE policy, th ese observations will available to the community
immediately.

ACS/HRC 9851

Host Galaxies of Reverberation-Mapped AGNs

We propose to obtain unsaturated ACS high-resolution images of all
reverberation-mapped active galactic nuclei in order to remove the
point-like nuclear light from each image, thus yielding a
"nucleus-free" image of the host galaxy. This will allow investigation
of host-galaxy properties: our particular interest is determination of
the host-galaxy starlight contribution to the reverberation mapping
observations, which is necessary for accurate determination of the
relationship between the AGN continuum flux and the size of the broad
Balmer-line emitting region of AGNs. Because this relationship is used
to estimate black-hole masses of large samples of distant AGNs,
correct determination of the slope of this relationship is critically
important.

ACS 9831

Multiplicity among brown dwarfs in the Pleiades cluster

We have compiled a sample of 32 confirmed brown dwarfs in the Pleiades
cluster. We propose to observe this sample with HST/ACS in SNAPSHOT
mode in order to search for very low mass multiple systems. Our goals
are: 1} to determine the occurrence and frequency of binary systems
among substellar objects, which hold important clues to the formation
and evolution mechanism{s} of ultracool and brown dwarfs, 2} to get an
estimate of the Initial Mass Function {IMF} at very low masses, which
is still unknown and very much needed to be corrected for binarity, 3}
to compare the distribution of multiple systems in young open clusters
and in the field.

NIC3/ACS/HRC/WFC 9803

Deep NICMOS Images of the UDF

The ACS Ultra Deep Field {UDF} images will greatly enhance the rich
suite of deep multi-wavelength images in the Chandra Deep Field South
{CDF–S}. We propose to complete the image set with deep near-IR
NICMOS images at 1.1 and 1.6 microns over a significant fraction of
the UDF, providing a critical link between the HST ACS and SIRTF
observations. The timely addition of the near-IR images ensures that
investigators will have images that span the spectrum from X-ray to
far IR. In recognition of the value of the near IR images this
proposal is submitted as a Treasury proposal with no proprietary
period. The proposal team will deliver science quality images,
mosaiced images covering 4.9 sq arc min, and a photometric catalog
complete to an AB mag of 28.2 in both the F110W and F160W filters. The
program also delivers a parallel extremely deep ACS field, 8′ away,
that reaches to within 0.6 mag of the UDF in the same filters as the
UDF. The scientific program of the proposal team focuses on the star
formation history of the universe, evolved galaxies at high redshift,
galaxies at the epoch of reionization, and the redshift evolution of
AGNs and ULIRGs. The HDF-N is currently the only field with
spatially-coincident deep HST imaging in both the optical and near-IR.
The small size of the HDF-N means that large scale structure is the
dominant error in the results from the HDF-N. Providing observations
in a field that is spatially uncorrelated is critically important. The
UDF/CDF-S fulfills that goal. The depth of the UDF ACS imaging, and
the wealth of Great Observatory and ground based observations in the
CDF-S, make these NICMOS observations uniquely valuable. An
extraordinarily rich array of science opportunities await the
community from the NICMOS UDF data.

NIC2 9801

Are OH/IR Stars the Youngest post-AGB stars? A NICMOS Imaging Survey

Essentially all well-characterized preplanetary nebulae {PPNe}–
objects in transition between the AGB and planetary nebula
evolutionary phases – are bipolar, whereas the mass-loss envelopes of
AGB stars are strikingly spherical. In order to understand the
processes leading to bipolar mass-ejection, we need to know at what
stage of stellar evolution does bipolarity in the mass-loss first
manifest itself. We have recently hypothesized that most OH/IR stars
{evolved mass- losing stars with OH maser emission} are very young
PPNe. We are conducting a multiwavelength survey program of imaging
and spectroscopic observations of such objects, using a large,
morphologically unbiased sample selected using IRAS 12-to-25 micron
colors. Our ongoing HST/SNAP imaging survey of the optically bright
half of this sample with WFPC2 and ACS is highly successful: 19/32
objects observed are extended with bipolar/multipolar shapes
{remaining objects are unresolved}. Slightly more than 50% of our
sample are optically too faint or undetected but have strong near-IR
counterparts — we therefore propose a NICMOS SNAPshot imaging survey
of these optically-faint OH/IR stars. These observations are crucial
for determining how and when the bipolar geometry asserts itself. The
results from our NICMOS survey {together with the WFPC2/ACS survey}
will allow us to draw general conclusions about the onset of bipolar
mass-ejection during late stellar evolution. Our complementary program
of interferometric mapping of the OH maser emission in our sources is
yielding kinematic information with spatial resolution comparable to
that in the HST images. The HST/radio data will provide crucial input
for theories of post-AGB stellar evolution. In addition, these data
will also indicate whether the multiple concentric rings, "searchlight
beams”, and truncated equatorial disks recently discovered with HST
in a few PPNe, are common or rare phenomena.

STIS 9786

The Next Generation Spectral Library

We propose to continue the Cycle 10 snapshot program to produce a Next
Generation Spectral Library of 600 stars for use in modeling the
integrated light of galaxies and clusters. This program is using the
low dispersion UV and optical gratings of STIS. The library will be
roughly equally divided among four metallicities, very low {[Fe/H] lt
-1.5}, low {[Fe/H] -1.5 to -0.5}, near-solar {[Fe/H] -0.3 to 0.1}, and
super-solar {[Fe/H] gt 0.2}, well-sampling the entire HR-diagram in
each bin. Such a library will surpass all extant compilations and have
lasting archival value, well into the Next Generation Space Telescope
era. Because of the universal utility and community-broad nature of
this venture, we waive the entire proprietary period.

ACS/WFC 9777

The environment of QSOs at the reionization epoch

Our goal is to elucidate the role of QSOs and galaxies at the tail end
of reionization by identifying z~6 galaxies near SDSS z>6 QSOs through
their red i-z colors. A similar technique was used by the SDSS to
identify the QSOs themselves. Based on our understanding of the growth
of structure in the Universe and on observations at z ~= 4, we expect
z~6 QSOs to be associated to the high peaks in the matter density
distribution. Therefore, they should be surrounded by an excess of
objects – as compared to random fields – unless the ionizing radiation
from the QSOs themselves is inhibiting star formation. We will
concentrate on 5 QSOs discovered by the SDSS at z>~6 and spend 7
orbits with ACS on each of the QSO fields {2.5 in F775W – i – and 4.5
in F850LP – z}, for a total of 35 orbits. The exposures are optimized
for the detection of objects with i-z> 2. The reference properties of
the field population will be provided by GOODS which is reaching the
same depth. The proposed observations will be capable of revealing the
dominant effect between galaxy suppression by the QSO ionizing flux
and number density excess due to clustering. We will test whether the
balance between suppression and enhancement evolves with redshift. We
will also be able to estimate for these fields the ionizing continuum
contribution by galaxies and compare it with that of the QSOs. If
galaxies are found to be comparably important to QSOs in these
selected fields, the idea that hydrogen reionization is primarily due
to stellar radiation would be significantly strengthened.

ACS/HRC 9747

An Imaging Survey of the Statistical Frequency of Binaries Among
Exceptionally-Young Dynamical Families in the Main Asteroid Belt

We propose an ambitious SNAPSHOT program to determine the frequency of
binaries among two very young asteroid families in the Main Belt, with
potentially profound implications. These families {of C- and S-type}
have recently been discovered {Nesvorny et al. 2002, Nature 417, 720},
through dynamical modeling, to have been formed at 5.8 MY and 8.3 MY
ago in catastrophic impact events. This is the first time such
precise and young ages have been assigned to a family. Main-belt
binaries are almost certainly produced by collisions, and we would
expect a young family to have a significantly higher frequency of
binaries than the background, because they may not yet have been
destroyed by impact or longer-term gravitational instabilities. In
fact, one of the prime observables from such an event should be the
propensity for satellites. This is the best way that new numerical
models for binary production by collisions {motivated largely by our
ground-based discoveries of satellites among larger asteroids}, can be
validated and calibrated. HST is the only facility that can be used to
search for binaries among such faint objects {V>17.5}. We will also
measure two control clusters, one being an "old" family, and the other
a collection of background asteroids that do not have a family
association, and further compare with our determined value for the
frequency of large main-belt binaries {2%}. We request visits to 180
targets, using ACS/HRC.

ACS/HRC 9721

The Kinematics and Dynamics of the Material Surrounding Eta Carinae

We propose a series of observations using ACS/HRC that will perform
astrometric measurements of the ejecta around eta Car. We will observe
ejecta in three distinct regions: the inner {characterized by the
close-in debris such as the Weigelt blobs}, the intermediate
{primarily the equatorial disk}, and the outer {the homunculus and the
North and South Jet structures}. These observations will provide
second and third epoch measurements vs. previous WFPC2 data. The
resultant significantly increased temporal baseline {with
corresponding decreases in proper motion, date of origin and 3D
orientation errors} will allow for the detection of acceleration and
non-radial motion in the ejecta, testing the canonical hypothesis of
ballistic motion. A secondary goal of the observations will be to
compare the HRC measurements with concurrent Cycle 12 WFPC2
measurements taken by other observers {who have indicated they will
release their data immediately} is order to provide a calibration link
between the WFPC2 and HRC astrometric frames. Our proposed HRC
observations will require three HST orbits.

WFPC2 9712

Pure Parallel Near-UV Observations with WFPC2 within High-Latitude ACS
Survey Fields

In anticipation of the allocation of ACS high-latitude imaging
survey{s}, we request a modification of the default pure parallel
program for those WFPC2 parallels that fall within the ACS survey
field. Rather than duplicate the red bands which will be done much
better with ACS, we propose to observe in the near-ultraviolet F300W
filter. These data will enable study of the rest-frame ultraviolet
morphology of galaxies at 0<z<1. We will determine the morphological
k-correction, and the location of star formation within galaxies,
using a sample that is likely to be nearly complete with
multi-wavelength photometry and spectroscopic redshifts. The results
can be used to interpret observations of higher redshift galaxies by
ACS.

WFPC2 9709

POMS Test Proposal: WFII parallel archive proposal

This is the generic target version of the WFPC2 Archival Pure Parallel
program. The program will be used to take parallel images of random
areas of the sky, following the recommendations of the 2002 Parallels
Working Group.

GO 9406

GD 552: The Oldest Cataclysmic Variable

A terrible puzzle has long afflicted our understanding of the
evolution of cataclysmic variables {CVs}. Angular momentum loss should
grind the binaries down to orbital periods near 1.3 hr in 2 — 4 Gyr,
and then slowly drive them apart again. Most CVs should therefore have
undergone “period bounce" long ago, and be evolving towards longer
period, with secondaries << 0.1 M_odot. However, not a single
post-bounce CV has been conclusively identified. Where are the old CVs
hiding? They should be hard to find since they’re probably faint
intrinsically, and because their accretion rates may be too low to
trigger dwarf-nova eruptions. One, and only one, good candidate
appears in the Lowell proper-motion lists. This is GD 552:
noneruptive, possessing a light secondary, and probably the least
luminous CV yet found {M_V >~ +12.5}. An accurate FGS parallax will
establish whether this object {clearly very nearby} signifies a large
population of very old CVs. A 1200 — 10000 Angstrom spectrum would
likely represent a pure steady-state low-dot M disk {the only one
known}, and the FUV region would provide a measurement of T_ eff in a
white dwarf long after eruptive heating episodes have stopped. The UV
observation obviously requires HST, and efforts to measure the
parallax from the ground are thwarted by a background star 0^ .7
distant.

NIC1/NIC2/NIC3 8792

NICMOS Post-SAA calibration – CR Persistence Part 3

A new procedure proposed to alleviate the CR-persistence problem of
NICMOS. Dark frames will be obtained immediately upon exiting the SAA
contour 23, and every time a NICMOS exposure is scheduled within 50
minutes of coming out of the SAA. The darks will be obtained in
parallel in all three NICMOS Cameras. The POST-SAA darks will be
non-standard reference files available to users with a USEAFTER
date/time mark. The keyword ‘USEAFTER=date/time’ will also be added to
the header of each POST-SAA DARK frame. The keyword must be populated
with the time, in addition to the date, because HST crosses the SAA ~8
times per day so each POST-SAA DARK will need to have the appropriate
time specified, for users to identify the ones they need. Both the raw
and processed images will be archived as POST-SAA DARKSs. Generally we
expect that all NICMOS science/calibration observations started within
50 minutes of leaving an SAA will need such maps to remove the CR
persistence from the science images. Each observation will need its
own CRMAP, as different SAA passages leave different imprints on the
NICMOS detectors.

WFPC2 10082

POMS Test Proposal: WFII backup parallel archive proposal

This is a POMS test proposal designed to simulate scientific plans

WFPC2 10075

WFPC2 CYCLE 12 Intflat and Viflat Sweeps and Filter Rotation Anomaly
Monitor

Using intflat observations, this WFPC2 proposal is designed to monitor
the pixel-to-pixel flatfield response and provide a linearity check.
The intflat sequences, to be done once during the year, are similar to
those from the Cycle 11 program 9597. The images will provide a backup
database in the event of complete failure of the visflat lamp as well
as allow monitoring of the gain ratios. The sweep is a complete set of
internal flats, cycling through both shutter blades and both gains.
The linearity test consists of a series of intflats in F555W, in each
gain and each shutter. As in Cycle 11, we plan to continue to take
extra visflat, intflat, and earthflat exposures to test the
repeatability of filter wheel motions.

WFPC2 10069

WFPC2 CYCLE 12 Supplemental Darks, Part 1/3

This dark calibration program obtains 3 dark frames every day to
provide data for monitoring and characterizing the evolution of hot
pixels.

WFPC2 10067

WFPC2 Cycle 12 Decontaminations and Associated Observations

This proposal is for the monthly WFPC2 decons. Also included are
instrument monitors tied to decons: photometric stability check, focus
monitor, pre- and post-decon internals {bias, intflats, kspots, &
darks}, UV throughput check, VISFLAT sweep, and internal UV flat
check.

ACS/WFC 10055

ACS Polarization Calibration

This proposal aims to address several specific issues for the
polarization calibration: {1} variations in calibration with position
on the detector {field dependence}, {2} dependence on telescope
roll-angle relative to the target, {3} orientation of the polarizer
axes, and {4} geometric distortion contributed by the polarizers.

ACS/HRC/WFC 10042

CCD Daily Monitor

This program consists of basic tests to monitor, the read noise, the
development of hot pixels and test for any source of noise in ACS CCD
detectors. This programme will be executed once a day for the entire
lifetime of ACS.

STIS/CCD 10019

CCD Bias Monitor – Part 1

Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1,
and 1×1 at gain = 4, to build up high-S/N superbiases and track the
evolution of hot columns.

STIS/CCD 10017

CCD Dark Monitor-Part 1

Monitor the darks for the STIS CCD.

WFPC2/ACS/HRC/WFC 10013

Focus Monitor

The focus of HST is measured from WFPC2/PC and ACS/HRC images of
stars. Multiple exposures are taken in parallel over an orbit to
determine the influence of breathing on the derived mean focus.
Observations are taken of clusters with suitable orientations to
ensure stars appear in all fields.

STIS/CCD 10000

STIS Pure Parallel Imaging Program: Cycle 12

This is the default archival pure parallel program for STIS during
cycle 12.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary
reports of potential non-nominal performance that will be
investigated.)

HSTAR 9208: GS Acquisition (2,1,1) @ 320/16:41:35Z ended in FL backup
(2,0,2) due to SSLE on FGS 1 @ 320/16:45:08Z. GS Reacquisition @
320/18/25:50Z also ended in FL backup. Under investigation.

COMPLETED OPS REQs: NONE

OPS NOTES EXECUTED:

  • 1173-0 Change Limits MAMA1 Threshold Voltage @ 318/10:20z
  • 1135-2 Battery Pressures Ground Limits @ 318/21:30z
  • 1174-0 Adjust Error Count limit @ 320/05:50z
  • 1173-0 Change Limits MAMA1 Threshold Voltage @ 321/05:33z

                       SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS GSacq           24                        24
FGS REacq           20                        20
FHST 
Update         51                        50              319/15:29:01z  2rd 
FM failed.
LOSS of LOCK

SIGNIFICANT EVENTS: None

SpaceRef staff editor.